Cardiac lead with helix suture sleeve

ABSTRACT

An implantable therapy lead is disclosed herein. In one embodiment, the therapy lead includes an elongated lead body and a suture sleeve. The elongated lead body has a proximal region and a distal region opposite the proximal region. The suture sleeve is supported on the lead body and has a proximal end, a distal end opposite the proximal end, an outer surface extending between the proximal end and distal end, and an inner surface radially inward of the outer surface and extending between the proximal end and distal end. The inner surface defines a lumen through which the elongated lead body extends. A helical structure helically extends about a longitudinal center axis of the lumen and along the inner surface.

FIELD OF THE INVENTION

The present invention relates to medical apparatus and methods. Morespecifically, the present invention relates to implantable therapy leadsand methods of assembling such leads.

BACKGROUND OF THE INVENTION

An implantable cardiac pulse generator (e.g., pacemaker, implantablecardioverter defibrillator (ICD), or etc.) is typically electricallycoupled to therapy locations in the heart via elongated implantablecardiac leads that can be advanced into the patient's heart. The leadsinclude electrodes to sense electrical activity and deliver therapeuticstimulation to heart tissue

A suture sleeve is supported on the elongated body of each lead andsubcutaneously fixates the lead to body tissue. By anchoring the lead tothe patients' body, movement of the lead body can be mitigated thusreducing the prevalence of dislodgements.

In some instances, suture sleeves have been known to slide after beingsutured to the body tissue. To help reduce the possibility of slippage,physicians have been known to apply excessive tie-down force to thesutures and, as a result, end up damaging the lead, thereby resulting inelectrical noise. Also, in order to re-position the suture sleeve, thesuture must be clipped and re-tied which presents an opportunity todamage the lead body from re-tying of the suture as well as potentiallyclipping the lead outer tubing during removal.

Numerous solutions have been created to address these suture sleeveissues, but none have proven to be cost effective. Accordingly, there isa need in the art for an improved suture sleeve and related methods ofuse and manufacture.

SUMMARY

An implantable therapy lead is disclosed herein. In one embodiment, thetherapy lead includes an elongated lead body and a suture sleeve. Theelongated lead body includes a proximal region and a distal regionopposite the proximal region. The suture sleeve is supported on the leadbody and includes a proximal end, a distal end opposite the proximalend, an outer surface extending between the proximal end and distal end,and an inner surface radially inward of the outer surface and extendingbetween the proximal end and distal end. The inner surface defines alumen through which the elongated lead body extends. A helical structurehelically extends about a longitudinal center axis of the lumen andalong the inner surface.

In one version of the embodiment, the helical structure includes ahelical recess defined in the inner surface and projecting radiallyoutward from inner surface. In one version of the embodiment, thehelical structure includes a helical protrusion extending along theinner surface and projecting radially inward from inner surface. In oneversion of the embodiment, the helical structure can include both thehelical recess and the helical protrusion.

In one embodiment, the therapy lead includes an elongated lead body anda suture sleeve. The elongated lead body includes a proximal region anda distal region opposite the proximal region. The suture sleeve issupported on the lead body and includes a proximal end, a distal endopposite the proximal end, an outer surface extending between theproximal end and distal end, an inner surface radially inward of theouter surface and extending between the proximal end and distal end, anda structure. The inner surface defines a lumen through which theelongated lead body extends. The structure at least one of projectsradially inward from the inner surface or projecting radially outwardfrom the inner surface.

In one version of the embodiment, the structure projects radially inwardfrom the inner surface and includes a protrusion, and this protrusioncan include a helical aspect. In one version of the embodiment, thestructure projects radially outward from the inner surface and includesa recess defined in the inner surface, and this recess can include ahelical aspect. In one version of the embodiment, the helical structureincludes both the recess and the protrusion, and one or more of thesemay be helical or not.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various aspects, all withoutdeparting from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an embodiment of a lead, wherein an activefixation anchor of the lead is shown in an extended or deployed state.

FIG. 2 is an isometric view of an embodiment of a suture sleeve capableof being employed on a lead similar to that depicted in FIG. 1.

FIG. 3 is a longitudinal side view of the suture sleeve.

FIG. 4 is a longitudinal cross section of the suture sleeve taken alongsection line 4-4 in FIG. 2.

FIGS. 5A and 5B are, respectively, a longitudinal side view of thesuture sleeve depicting its appearance in an untied state and the sameside view of the suture sleeve except depicting its appearance in tiedstate.

FIG. 6A is a longitudinal side view of the suture sleeve.

FIGS. 6B-6D are, respectively, transverse cross sections of the suturesleeve taken along each of the three circumferential recesses at sectionlines 6B-6B, 6C-6C and 6D-6D in FIG. 6A.

FIG. 6E is an end elevation view of the suture sleeve as taken alongline 6E-6E in FIG. 6A.

FIG. 7 is a graph depicting comparison dry untied pull test results fora control sleeve having no helix structure and being identical to asuture sleeve used in the industry and the helical structure equippedsuture sleeve depicted in FIGS. 2-6E.

FIG. 8 is a graph depicting comparison wet tied pull test results for acontrol sleeve having no helix structure and being identical to a suturesleeve used in the industry and the new helical structure equippedsuture sleeve depicted in FIGS. 2-6E.

DETAILED DESCRIPTION

Implantable therapy leads 10 (e.g., a CRT lead, etc.) and methods ofusing and manufacturing such leads are disclosed herein. In oneembodiment, the therapy lead 10 includes a suture sleeve 34 supported onthe elongated body 12 of the lead. The suture sleeve 34 includes helicalfeatures 110, 112 defined in the interior surface 106 that defines thelumen 108 of the suture sleeve and through which the lead body 12extends.

When the suture sleeve is sutured to the lead body, the helical internalfeatures 110, 112 of the suture sleeve 34 gently manipulate the leadbody 12 into a corkscrew shape. The helical contouring shape changes theway the forces are distributed along the lead body, affectivelyincreasing the resistance to slipping between the suture sleeve and thelead body.

In an untied condition, the helical internal features 110, 112 alsoallow for the suture sleeve 34 to be repositioned easily along the leadbody 12, the resistance to slipping of the helical internal featuresonly manifesting itself when the suture sleeve is sutured. This sutureinduced resistance to slipping of the helical features of the suturesleeve is advantageous as a suture sleeve in the untied condition shouldideally slide easily along the lead body.

The helical internal features 110, 112 of the suture sleeve 34 may be inthe form of a helical trough or recess 110 and a helical ridge orprotrusion 112, both of which are measured against the rest of the innercircumferential surface 106 of the lumen 108 of the suture sleeve 34.The two helical features 110, 112 may have the same general helicalpitch and a generally constant offset. The helical recess 110 acts as awindow-like feature to allow the silicone (or similar material formingthe suture sleeve 34) to deform and maintain grip along the lead body.Without such a window-like feature 110, when the silicone is constrictedby the suture tie, it will form into an oval-like shape and notcircumferentially grip the lead body 12. The window-like feature 110acts as a space for the silicone to move into and help the siliconecontact the lead body 12 uniformly.

a. Overview of Lead

To begin a detailed discussion of the lead 10, reference is made to FIG.1, which is a plan view of an embodiment of the lead 10. While thefollowing overview of the lead is given in the context of an activefixation lead, the teachings herein are equally applicable to passivefixation leads, and the present disclosure should not be limited toactive fixation leads. Instead, the present disclosure should beinterpreted as encompassing implantable leads of all types and of allfixation mechanisms, including passive fixation mechanisms in additionto active fixation mechanisms.

As can be understood from FIG. 1, in one embodiment, the lead 10 isdesigned for intravenous insertion and contact with the endocardium, andas such, may be conventionally referred to as an endocardial lead. Inother embodiments, the lead 10 may be of other configurations for otherimplantation types, such as, for example, leads implanted in theintrapericardial space.

As indicated in FIG. 1, the lead 10 is provided with an elongated leadbody 12 that extends between a proximal region 14 and distal region 16of the lead 10. The proximal region 14 of the lead 10 includes aconnector assembly 18, which is provided with sealing rings 20 andcarries at least one or more electrical connectors in the form of ringcontacts 22 and a pin contact 24. The connector assembly 18 isconfigured to be plugged into a receptacle of a pulse generator, thesealing rings 20 forming a fluid-tight seal to prevent the ingress offluids into the receptacle of the pulse generator. When the connectorassembly 18 is plugged into the pulse generator receptacle, the contacts22, 24 electrically connect with the circuitry of the pulse generatorsuch that electrical signals can be administered and sensed by the pulsegenerator via the electrical pathways of the lead 10.

The connector assembly 28 is constructed using known techniques and ispreferably fabricated of silicone rubber, polyurethane,silicone-rubber-polyurethane-copolymer (“SPC”), or other suitablepolymer. The electrical contacts 22, 24 are preferably fabricated ofstainless steel or other suitable electrically conductive material thatis biocompatible.

As shown in FIG. 1, the distal region 16 of the lead 20 includes thehelical active fixation anchor 26 distally extending from an extremedistal tip end 28 of the lead 20 when the active fixation anchor 26 isin a deployed state. The anchor 26 may be transitioned to a non-deployedstate via retraction of the anchor 26 into the confines of the distalregion 16 of the lead 10 or by an obturator or other structural memberbeing combined with the anchor 26 to inhibit the anchor 26 from beingable to penetrate tissue.

In one embodiment, the anchor 26 is deployed or placed in the extendedstate by rotating the contact pin 24, which is coupled via a helicalconductor to the anchor 26. As the contact pin 24 is rotated about itslongitudinal axis, the helical conductor and sharp helical anchor 26rotate relative to the rest of the lead 10 to cause the anchor 26 toextend from the lead distal end 28 to screw into myocardial tissue. Insome other embodiments, a stylet or other tool is inserted through thelead body 12 to deploy the anchor 26 via rotation and/or sliding distaldisplacement of the anchor 26 brought about by complementary interactionof the stylet or other tool with structural features of, or associatedwith, the anchor 26.

The anchor 26 may also be configured to act as an electrode in additionto providing active fixation to heart tissue. Where the anchor 26 isalso configured to act as an electrode, depending on the dictates of thepulse generator, the anchor 26 may be employed for sensing electricalenergy and/or administration of electrical energy (e.g., pacing). Theanchor 26 is electrically coupled to the pin contact 24 of the connectorassembly 18 via the electrical conductor extending through the lead body12 and the connector assembly 18, Depending on the embodiment, theelectrical conductor may be in the form of helically coned electricalconductors. In other embodiments, the conductor may be in the form ofwires, cables or other electrical conductors that are linear orhelically coiled in configuration.

The distal region 16 of the lead 10 also includes an annular ringelectrode 30 proximally offset from the extreme distal tip end 28 of thelead 10. Depending on the dictates of the pulse generator, this ringelectrode 30 may be employed for sensing electrical energy and/oradministration of electrical energy (e.g., pacing). The ring electrode30 is electrically coupled to one of the ring contacts 22 of theconnector assembly 18 via another electrical conductor extending throughthe lead body 12 and the connector assembly 18. This electricalconductor may also be in the form of helically coded electricalconductors. In other embodiments, this conductor may be in the form ofwires, cables or other electrical conductors that are linear orhelically coiled in configuration.

As indicated in FIG. 1, the lead 10 may include a fixation or suturesleeve 34 slidably mounted around the lead body 12. The suture sleeve 34serves to stabilize the pacing lead 10 at the site of venous insertion.

Where the lead 10 is equipped for defibrillation, a shock coil 36 willbe supported on the lead body 12 proximal the ring electrode 30 anddistal the fixation sleeve 34. The shock coil 36 is electrically coupledto one of the ring contacts 22 of the connector assembly 18 viaelectrical conductors extending through the lead body 12 in the form ofwires, cables or other electrical conductors that are linear orhelically coiled in configuration.

The lead body 12 includes an outer insulation sheath 38 and an innerinsulation sheath. The outer insulation sheath 38 is preferablyfabricated of silicone rubber, polyurethane, siliconerubber-polyurethane-copolymer (SPC), or other suitable polymer. Theinner insulation sheath may be formed of the same material as the outerinsulation sheath 39 or from another material such as, for example,polytetrafluoroethylene (“PTFE”). The insulation sheaths isolate theinterior components of the lead 10, including the electrical conductorsfrom each other. The outer insulation sheath 38 isolates the innercomponents of the lead 10 from the surrounding environment and may besingle or multi-layer construction.

The lead body 12 may be constructed to include a hollow interiorextending from the proximal region 14 to the distal region 16. Thehollow interior allows for the introduction of a stylet, guidewire orother device during implant, which is beneficial in allowing the surgeonto guide the otherwise flexible lead 10 from the point of venousinsertion to the myocardium.

b. The Helix Suture Sleeve

FIG. 2 is an isometric view of an embodiment of a suture sleeve 34capable of being employed on a lead 10 similar to that depicted in FIG.1, and FIG. 3 is a longitudinal side view of the suture sleeve. As shownin FIGS. 2 and 3, the sleeve 34 includes a proximal end 50, a distal end52 opposite the proximal end, and an outer surface 54 extending betweenthe proximal end and distal end. The outer surface 54 has a proximalconical region 56, a cylindrical middle region 58, and a distal conicalregion 60. The cylindrical middle region 58 includes one or morecircumferential troughs or recesses 62 defined in the outer surface 54and projecting radially inward from the outer surface. For example, inone embodiment, the cylindrical middle region 58 includes threecircumferential recesses 62 evenly spaced apart from each other alongthe length of the cylindrical middle region 58. In other embodiments,there may be a greater or lesser number of circumferential recesses 62along the length of the cylindrical middle region 58.

As can be understood from FIGS. 2 and 3, in one embodiment, eachcircumferential recess 62 has a semi-circular transverse cross sectionwith a recess diameter R_(DIA) of between approximately 0.15 inches andapproximately 0.24 inches. While the circumferential recess 62 is shownas having a semi-circular cross section in FIGS. 2 and 3, in otherembodiments, the transverse cross section of the circumferential recess62 may be triangular, rectangular, semi-elliptical, or etc.

FIG. 4 is a longitudinal cross section of the suture sleeve 34 takenalong section line 4-4 in FIG. 2. As can be understood from FIG. 4, thesleeve 34 also includes an inner surface 106 radially inward of theouter surface 54. The inner surface extends between the proximal end 50and distal end 52. The inner surface 106 defines a lumen 108 throughwhich the elongated lead body 12 extends, as indicated in FIG. 1. Theinner surface 106 is at least substantially if not completelycylindrical.

As shown in FIG. 4, the suture sleeve 34 also includes one or morehelical structures 110, 112 helically extending about a longitudinalcenter axis 114 of the lumen 108 and along the inner surface 106. One ofthe helical structures may be in the form of a helical recess 110defined in the inner surface 106 and projecting radially outward frominner surface.

In one embodiment, the helical trough or recess 110 includes arectangular transverse cross section having a recess depth R_(D) ofbetween approximately 0.008 inches and approximately 0.012 inchesrelative to the inner surface 106 and a transverse recess width R_(W) ofbetween approximately 0.04 inches and approximately 0.05 inches. Whilethe helical recess 110 is shown as having a rectangular transverse crosssection in FIG. 4, in other embodiments, the transverse cross section ofthe helical recess may be triangular, semi-circular, semi-elliptical, oretc.

As illustrated hi FIG. 4, the other of the helical structures may be inthe form of a helical ridge or protrusion 112 projecting radially inwardfrom the inner surface 106. In one embodiment, the helical protrusion112 includes a rectangular transverse cross section having a protrusionheight P_(H) of between approximately 0.008 inches and approximately0.016 inches relative to the inner surface 106 and a transverseprotrusion width P_(W) of between approximately 0.09 inches andapproximately 0.11 inches. While the helical protrusion 112 is shown ashaving a rectangular transverse cross section in FIG. 4, in otherembodiments, the transverse cross section of the helical recess may betriangular, semi-circular, semi-elliptical, or etc.

The pitch of the helical recess 110 may be between approximately 7threads per inch and approximately 11 threads per inch, and the pitch ofthe helical protrusion 112 may be between approximately 7 threads perinch and approximately 11 threads per inch. The pitches of the helicalrecess and helical protrusion may be the same, or may be different butnot so different that the helical recess and helical protrusionintersect.

As indicated in FIG. 4, the helical recess 110 and the helicalprotrusion 112 are helically staggered or offset relative to each other.In one embodiment, the offset spacing between immediately adjacent turnsof the helical recess and helical protrusion are equal, while in otherembodiments, the offset spacing may be different.

As can be understood from FIG. 4, the helical recess 110 and the helicalprotrusion 112 have different transverse widths. For example, in oneembodiment and as illustrated in FIG. 4, the helical protrusion 112 hasa transverse width P_(W) that is wider than the transverse width R_(W)of the helical recess 110. In other embodiments, the transverse width ofthe helical protrusion may be equal to or smaller than the transversewidth of the helical recess.

In one embodiment, as shown in FIG. 4, the transverse widths, height anddepth of the helical recess and helical protrusion may be constant alongtheir respective helical lengths. In other embodiments, any one or moreof the transverse widths, height or depth of the helical recess andhelical protrusion may vary along their helical lengths.

As can be understood from FIG. 4, in one embodiment, the helicalstructures 110, 112 and the circumferential recesses 62 overlap eachother along at least one location along a distal-proximal length of thesuture sleeve 34 and, more specifically in one embodiment, along thevast majority of their common distal-proximal extents.

FIGS. 5A and 5B are, respectively, a longitudinal side view of thesuture sleeve 34 depicting its appearance in an untied state and thesame side view of the suture sleeve 34 except depicting its appearancein tied state. As indicated in FIG. 5A, when the suture sleeve is in theuntied state, the suture sleeve is straight (i.e., not deflected) andsymmetrical about its longitudinal center axis. In contrast, on accountof its internal helical structures, when the suture sleeve is in thetied state, the suture sleeve is not straight (i.e., it is deflected)and it is not symmetrical about its longitudinal center axis, as can beunderstood from the finite element analysis line 150 extending thelength of the suture sleeve 34 in FIG. 5B. Specifically, the internalhelical structures 110, 112 create material offsets, which when acted onby the constrictive forces of the sutures used to tie down the suturesleeve 34 on the lead body 12, create an undulating shape inside thesuture sleeve to slightly bend or undulate the lead body and increasefriction between the interior of the suture sleeve and lead body.

As can be understood from FIGS. 6A-6E, which are, respectively, alongitudinal side view of the suture sleeve 34, transverse crosssections taken along each of the three circumferential recesses 62 atsection lines 6B-6B, 6C-6C and 6D-6D, and an end elevation view as takenalong line 6E-6E, the helical recess 110 and the helical protrusion 112are opposite each other at each circumferential recess 62 and helicallyrotate about the inner circumferential surface 106 of the lumen 108approximately 120 degrees from circumferential recess 62 to immediatelyadjacent circumferential recess 62. These three transverse crosssections of FIGS. 6B-6D illustrate the unequal distribution of mass ofthe suture sleeve within the lumen of the suture sleeve on account ofthe helical features. The helical configuration and it unequal massdistribution work to force the suture sleeve 34 to bend in athree-dimensional corkscrew shape when an exterior force is compressedabout the suture sleeve at these exterior circumferential recesses 62such as, for example, by sutures tying the suture sleeve to the leadbody.

Displacing a lead body through a convoluted shape, such as that depictedin FIG. 5B, is much more difficult than a cylindrical conduit. Thefrictional values are increased as a result of increased normal values.As the lead body moves through a bend, the normal values along the bendare greatly increased, thus increasing the friction and deformation ofthe lead body through the bend. This tortuosity is induced when thecircumferential recesses 62 are tied, and this tortuosity is shown viathe finite element line 150 of FIG. 5B.

FIG. 7 is a graph depicting comparison dry untied pull test results fora control sleeve having no helix structure and being identical to asuture sleeve used in the industry and the new helical structureequipped suture sleeve 34 depicted in FIGS. 2-6E. The untied test is ofinterest as it shows that a physician can quickly and easily positionthe suture sleeve to the desired location if the pull force is not toolarge or too small. For example, in one embodiment, a desirable sleevemaximum pull force on an untied and dry suture sleeve is 0.25 lbf, whilea pull force that is too small means the suture sleeve will slide whenthe lead is held in a vertical orientation.

As can be understood from a comparison of the untied pull force resultsof FIG. 7, the helical design is statistically identical (P<0.05) withrespect to the dry untied pull force needed to position along the leadwhile also staying stationary when held in the vertical position. Thisamount of pull force also allows useful relative testing because the“pre-load” on the suture sleeve prior to tie-down is the same. With thisin mind, any differences noted in the pull strength of the wet and tiedtests will be indicative of the variable changed.

FIG. 8 is a graph depicting comparison wet tied pull test results for acontrol sleeve having no helix structure and being identical to a suturesleeve used in the industry and the new helical structure equippedsuture sleeve 34 depicted in FIGS. 2-6E. The tied wet test is ofinterest to look at how the suture sleeve will perform in-vivo. As canbe understood from FIG. 8, in this worst-case scenario, the new helixsuture sleeve design performed one and a half times as well as thenon-helix control suture sleeve design.

In use, the suture sleeve 34 is slid on over the lead body 12 distal end16 and moved proximally along the lead body to a desired anchoring area.Once the lead distal end 16 is implanted as desired, the physician tiesa suture over each circumferential recess 62 to fixate the sleeve 34 tothe lead body 12. Typically, two to three circumferential recesses 62may be employed to secure the suture sleeve 34 in place on the lead body12. The physician then ties a relatively loose suture over the suturesleeve into adjacent tissue to fixate the lead body to the patient. Toremove the suture sleeve, the physician cuts the suture ties and eitherslides the suture sleeve to and over the distal end of the lead body orcan cut the suture sleeve in half and peel it away from the lead body.

In manufacturing the helix suture sleeve design of FIGS. 2-6E, thesuture sleeve can be made of silicone rubber, silicone rubberpolyurethane copolymer (“SPC”) polyurethane, etc. and can be cast,formed, molded, injection molded, or etc.

In general, while the invention has been described with reference toparticular embodiments, modifications can be made thereto withoutdeparting from the spirit and scope of the invention. Note also that theterm “including” as used herein is intended to be inclusive, i.e.“including but not limited to.”

What is claimed is:
 1. An implantable therapy lead comprising: anelongated lead body having a proximal region and a distal regionopposite the proximal region; and a suture sleeve supported on the leadbody and comprising: a proximal end; a distal end opposite the proximalend; an outer surface extending between the proximal end and distal end;an inner surface radially inward of the outer surface and extendingbetween the proximal end and distal end, the inner surface defining alumen through which the elongated lead body extends; and a helicalstructure helically extending about a longitudinal center axis of thelumen and along the inner surface.
 2. The lead of claim 1, wherein thehelical structure comprises a helical recess defined in the innersurface and projecting radially outward from inner surface.
 3. The leadof claim 2, wherein the helical recess comprises a rectangulartransverse cross section.
 4. The lead of claim 2, wherein the helicalrecess comprises a recess depth of between approximately 0.008 inchesand approximately 0.012 inches relative to the inner surface.
 5. Thelead of claim 1, wherein the helical structure comprises a helicalprotrusion projecting radially inward from the inner surface.
 6. Thelead of claim 5, wherein the helical protrusion comprises a rectangulartransverse cross section.
 7. The lead of claim 5, wherein the helicalprotrusion comprises a protrusion height of between approximately 0.008inches and approximately 0.016 inches relative to the inner surface. 8.The lead of claim 1, wherein the helical structure comprises: a helicalrecess defined in the inner surface and projecting radially outward fromthe inner surface; and a helical protrusion projecting radially inwardfrom the inner surface.
 9. The lead of claim 8, wherein the helicalrecess and helical protrusion are helically offset relative to eachother.
 10. The lead of claim 8, wherein the helical recess and helicalprotrusion have different transverse widths.
 11. The lead of claim 10,wherein the helical recess has a transverse width that is less than atransverse width of the helical protrusion.
 12. The lead of claim 1,wherein the inner surface is at least substantially cylindrical.
 13. Thelead of claim 1, wherein the suture sleeve further comprises acircumferential recess defined in the outer surface and projectingradially inward from the outer surface.
 14. The lead of claim 13,wherein the helical structure and the circumferential recess overlapeach other along at least one location along a length of the suturesleeve.
 15. The lead of claim 1, further comprising a pulse generatorconfigured to electrically couple with the lead.
 16. An implantabletherapy lead comprising: an elongated lead body having a proximal regionand a distal region opposite the proximal region; and a suture sleevesupported on the lead body and comprising: a proximal end; a distal endopposite the proximal end; an outer surface extending between theproximal end and distal end; an inner surface radially inward of theouter surface and extending between the proximal end and distal end, theinner surface defining a lumen through which the elongated lead bodyextends; and a structure at least one of projecting radially inward fromthe inner surface or projecting radially outward from the inner surface.17. The lead of claim 16, wherein the structure projects radially inwardfrom the inner surface and includes a protrusion.
 18. The lead of claim17, wherein the protrusion comprises a helical aspect.
 19. The lead ofclaim 16, wherein the structure projects radially outward from the innersurface and has a recess defined in the inner surface.
 20. The lead ofclaim 17, wherein the recess comprises a helical aspect.